关键词: 模具, 结构化表面, 低雷诺数湍流模型, 软性磨粒流加工

Abstract:

To solve the difficulty in simulating flow characteristics,especially characteristics near the wall,during the precise soft abrasive flow machining of  the structural surfaces of molds, a method based on improved low-Reynolds-number turbulence model was proposed herein. This improved model could simulate turbulences of both high and low-Reynolds numbers, thus had  higher simulation precision for the wall regions.U-shaped groove, a common machining workpiece, was selected as the object of the simulation. In the experiments,the internal flow field of the U-shaped groove,
especially the flow characteristics near the wall, was simulated numerically. The analyses show that when initial pressure p0 is in the range of 2.5MPa to 4.5MPa, the internal flow is incompletely developed turbulence. The internal flow when p0 is 4.5MPa is analyzed in detail. It is found that in the flow path, both the pressure and velocity are higher at the center and lower on sides. In addition, pressure and velocity are higher in regions closer to the bottom of the U-shape. As the velocity of the abrasive flow increases, the driving force on the abrasive particles also increases, thus more particles collide with the wall per unit time. The collision experiments demonstrate that the abrasive particles' velocity of collision with the wall calculated by simulation is in accordance with the experimental data,and the machining experiments further validated the numerical simulation results.

Key words: mold, structural surface, low-Reynolds-number turbulence model, soft abrasive flow machining